1. Technical Field
The invention relates to an electroconductive roll, a charging device, a process cartridge, and an image forming apparatus.
2. Related Art
In the image forming apparatus using an electrophotographic system, after an image holding body is charged by a charging roll and a latent image is formed by irradiating the charged image holding body with laser beam or the like, the latent image is developed with toner to form a visualized toner image. Thereafter, the obtained toner image is transferred to a transfer member. Examples of the transfer member include an intermediate transfer body and a recording medium. When the image forming apparatus has an intermediate transfer body, the toner image held on an image holding body is transferred to the intermediate transfer body by a primary transfer roll, and then the toner image is transferred to a recording medium by using a secondary transfer roll or a backup roll. When the image forming apparatus has no intermediate transfer body, a toner image formed on an image holding body is transferred to a recording medium by using a transfer roll. The toner image transferred to the recording medium is fixed by a fixing device, thereby forming an image on a recording medium.
In the image forming apparatus, electroconductive rolls such as the charging roll or transfer rolls such as the primary transfer roll, the secondary transfer roll or the backup roll are in a state of being respectively in contact with an exterior member, at which an electric field is formed, and charge the exterior member or transfer toner image. Herein, the “exterior member” for the charging roll is an image holding body, and that for the transfer roll is the image holding body or an intermediate transfer body.
The electroconductive rolls are used in a state of being respectively in contact with exterior members such as an image holding body or an intermediate transfer body. Therefore, it is preferable that the surface of the electroconductive rolls are not deteriorated even when being used over a long period of time.